(1) Field of the Invention
The present invention relates to devices for handling articles in general and more particularly to automatic devices for depalletizing/palletizing boxes and manipulating them, for instances, for transferring them from one position to another as on an assembly line.
(2) Prior Art
In order to reduce product cost, improve product quality and increase product throughout, the current trend in industry is to automate the assembly lines that manufacture the product. Automated assembly lines necessitate the use of robotic systems for performing tasks that were formerly done by humans. A fully automated assembly line includes a conveyor system with a plurality of workstations disposed along the conveyor system. The conveyor system transports the components that are used to manufacture the product while the actual fabrication of the product is done at the different workstations.
Each workstation is fitted with a robotic system designated to perform an assigned task. Included in the assigned task is the depalletizing of boxes. Usually, the boxes carry the components that are used in the fabrication of a particular product. Other tasks include opening the boxes, removing the components from the boxes, assembling the component in a finished product, testing the product, packaging the product, and palletizing the product for shipment to the ultimate user.
The typical robotic system includes a robot and an article handling system connected to the robot. The article handling system is usually designed to handle and/or manipulate the article while the robot is the mechanism that move the article handling system and its attached article to a designated point. Article handling systems may be broadly classified into two types, namely: the gripping type and the lifting type.
The gripping type article handling systems invariably include a gripping mechanism that attaches to the top of an article, such as a box, and moves said article from one position and/or place to the next. Such gripping mechanism may include suction cups to which a source of negative pressure is applied to effectuate attachment to the article. Alternately, attachment may occur by magnetic means and/or mechanical means. U.S. Pat. Nos. 4,266,905; 4,299,533; 4,242,025 and 4,392,766 describe gripping mechanisms in which negative pressure is used to effectuate attachment.
On the other hand, the lifting type article handling systems may be considered to be reminiscent of the fork lift devices used in warehouses to move articles. Such devices consist of a pair of spaced forks or lifting elements which are inserted under the bottom side of the article. As a result, the article sits on the forks and is relocated.
Although the above identified article handling systems work well for the intended purpose, they all handle the boxes from either the top side or the bottom side and as such are not suitable for use on the type of automated manufacturing lines wherein the components for manufacturing the product are provided in boxes (such as cartons) having removable covers (shoe box style). Since the top covers are loose, such cartons cannot be handled and/or depalletized by holding onto the covers.